concerned for my son

i am researching some on turrets because of some symptoms my 6 year old little boy is having but havent been able to find an answer yet so if anyone can tell me i would really appreciate it...... a few months ago my little boy started making these grunting sounds in his throat at first i thought he was just making them to be making them but now its gotten worse and he says its not a habit he started and he isnt able to stop doing it. other kids and adults have noticed him making the sounds and call him out on it and he just trys not to do it and seems its getting worse. i can tell he doesnt do it on purpose cause he is starting to look sad and says im trying not to mom even though i encourage him it will be ok and to not think and worry on it so much ive noticed when someone says something about him doing it it gets more constant and if he is nervous or seems to be thinking on something thats on his mind it becomes more constant. so there is some of his story:) NOW MY QUESTION IS COULD THIS BE A SYMPTOM OF TURRETS? OR, DOES ANYONE KNOW WHAT IT COULD BE A SIGN OR SYMPTOM OF?  please respond and tell me something useful so maybe i can figure out what it is and explain to him a little bit about what could be going on we have a doctor appointment but its a little while away:(                                          thanks,